In my previous apartment, the landlady had zero sense of decency and would let herself in to snoop around.

I use these devices because I can factually know that nobody has entered my home while I was gone. It is peace of mind. I don't think about burglaries or whatever. I think about how my landlord or a property manager or rotating cast of anonymous maintenance people have a key and the only reason they don't abuse it is because of decency.